Ribonuclease is an enzyme. Its secondary structure contains both -helices and -pleated sheets. a. i. Describe the

Ribonuclease is an enzyme. Its secondary structure contains both α-helices and β-pleated sheets.

a. i. Describe the structure of a typical α-helix.

ii. Describe the structure of a typical β-pleated sheet.

b. The single polypeptide chain of ribonuclease contains four disulfide bridges. Draw the structure of a disulfide bridge.

c. Describe how van der Waals’ forces between amino acid side-chains help to stabilise the tertiary structure of a protein. In your answer refer to the type of side-chains involved.